If scientists can successfully create human sperm in the laboratory we could potentially start finding answers to a number of questions: why some men don't make sperm or why the sperm they do make don't work properly; how we could generate newer chemotherapy drugs that don't make men infertile after cancer treatment; why sperm counts might have declined in recent years. It could even help to develop the new contraceptive for men that women have long been demanding. And being able to observe the processes of sperm development in this new way could one day allow doctors to overcome male fertility in unique and novel ways.

So, if correct, the claims made by Newcastle University would be a major advance for sperm biology and we are right to be excited by it. However, having looked down the microscope to observe sperm almost every day for the past 20 years, I cannot correlate what I see in the news with what I understand a mature human sperm to be.

While the cells that the Newcastle group have generated may possess some of the distinctive genetic features and molecular markers seen in mature human sperm, ejaculated sperm have specific cellular morphology, behaviour and physiology that are not described in this paper.

For example, I have looked at the video that accompanies the paper but it is of insufficient resolution for me to observe how these cells are actually moving. Since movement is an important part of sperm behaviour, it would seem important to assess this in some detail.

In addition, because the structural elements of ejaculated sperm are very distinctive, I would like to see thin sections of the putative sperm examined with an electron microscope and compare them to how we know the head, mid-piece and tail of mature sperm are constructed.

Perhaps this data is in their next paper and if it is, I look forward to reading it. I am open to being convinced that these cells are indeed sperm. But for now I can only agree that they are "sperm-like" and I urge caution about the findings until we know more.

The inevitable consequence of this research generating such high-profile news is that infertile couples may seize it upon as a new possible solution to their infertility. I have already received several emails from men (and women) asking when it will be available to help them. I have to be honest and tell them that this may be never be the case.

Although the Newcastle researchers have been clear in their press release that it is not the immediate intention of their work to create functional sperm for infertile couples to use to make babies, I do worry that the hopes of patients may have been raised by the intensity of the press reporting of this story. The headline "Early stage sperm-like cells created" is not as sexy as "British scientists create human sperm" but is more accurate and would have confined this story to the inside pages where it belongs. This science is important and rightly deserves attention but splashing it on the front pages could be said to be somewhat premature.

Infertility causes much distress and for too long has been the poor relation of other diseases in terms of attracting NHS funding and resources. As scientists working in this field, we need to always remember to be cautious when reporting our findings and be mindful that we do not give false hope to the very patients we are trying to help.